Supernova Left Its Mark In Ancient Bacteria

ananyo writes "Sediment in a deep-sea core may hold radioactive iron spewed by a distant supernova 2.2 million years ago and preserved in the fossilized remains of iron-loving bacteria. If confirmed, the iron traces would be the first biological signature of a specific exploding star. Scientists have found the isotope iron-60, which does not form on Earth, in a sediment core from the eastern equatorial Pacific Ocean, dating to between about 1.7 million and 3.3 million years ago. The iron-60, which appears in layers dated to around 2.2 million years ago, could be the remains of magnetite chains formed by bacteria on the sea floor as radioactive supernova debris showered on them from the atmosphere, after crossing inter-stellar space at nearly the speed of light."

Comments

I'm not saying it's aliens, but...

[DougOtto]

it's aliens.

One supernova of many in Local Bubble

[Morgaine]

Our solar system resides in an area of our galaxy called the "Local Bubble", roughly a few hundred lightyears across. This region is very empty compared to the average interstellar medium in the galaxy, as a result of a large number of supernovae that blew out a sort of cavity in our interstellar neck of the woods long ago. In actual structure it's more of an irregular "Local Chimney" going right through the galactic disc rather than a spherical bubble.

As a result, pinning the cause of TFA's observations to a single supernova is not all that simple, as supernovae were very common in the Sun's general neighborhood in our galactic past..

Here's a nice graphic of the larger features in and around our local bubble. It's a fascinating subject if you enjoy understanding our location in a galactic context.

Re:One supernova of many in Local Bubble

[argStyopa]

It's one of the few (to me) persuasive arguments that life might be quite rare, in that so many other ways our sun and system is apparently entirely pedestrian.

Our seemingly interesting local neighborhood and circumstances for only the last 5-10 million years might mean that intelligent life - on this planet at least - might be existing only in what (on a galactic scale) amounts to a spark floating for a moment in the flickering gap between tongues of a campfire's flame.

It's humbling, really.

Re:One supernova of many in Local Bubble

[Anonymous Coward]

It's one of the few (to me) persuasive arguments that life might be quite rare

Rare? What are you talking about? The Earth gets blasted by supernovas, and all we get is some minor deposits in a geological layer. Not even a major extinction. Nothing.

I would say it shows that life is much more resilient than people think. And the Local Bubble just shows how common it must be.

If anything, I would not be surprised if there is active and viable life forms living underground on Mars. Atmosphere blown away? No problem! Just live underground. All life needs is some catalysts, chemicals and a temperature gradient keeping these chemicals in a proper state.

Re:One supernova of many in Local Bubble

[smpoole7]

> life might be quite rare ...
and ...
> life is much more resilient ...

I'm going to split the difference between you two. I just finished reading John Gribbin's "Alone In The Universe: Why Our Planet Is Unique." Yes, it's another rehash of the "Rare Earth" hypothesis, but he bases it on some of the latest computer simulations.

Gribbin says that *simple single-celled life* might be very common throughout our Galaxy. But Gribbin makes the argument that *sentient* life is probably quite rare.

You may not agree with his conclusion, but he presents the latest evidence and theories for solar system formation. Well worth the read.

Re:One supernova of many in Local Bubble

[Anonymous Coward]

From his metaphor of the spark and the campfire flames, I suspect that the parent meant that for the last several tens of thousands of years of our solar system's voyage through space, we've enjoyed the relative peace and quiet of the Local Bubble's emptiness.

Prior to that, it wasn't always this quiet. The rate of accreted objects from the denser molecular clouds through which we travelled hitting us, as well as the perturbation of the Sun's distant outliers sending them inwards at a higher rate than now, both would have raised the frequency of material reaching our surface, sometimes catastrophically.

Under such conditions, the probability of cosmic extinction events for a planet with life is clearly higher than at present. The current (6th) mass extinction event is orders of magnitude worse but it does not have a cosmic cause, being man-made, so it's not germane to the emptiness of the Local Bubble.

Our disastrous custodianship of the planet aside, there was no shortage of cosmic threats to the survival of our biosphere not long ago.

Re:One supernova of many in Local Bubble

[Anonymous Coward]

Before you get humbled much further, consider that life has existed on this planet for billions of years. By comparison, Wikipedia places the age of the bubble at ten to twenty million years. In other words, dinosaurs went extinct more than three times as long ago as the bubble has been in existence. Primates had already evolved by the time the bubble came into existence, and early protohumans were using stone tools by the time the Earth was being showered by the radioactive iron the article talks about.

Suprnova is gone

[Spy Handler]

but piratebay and isohunt are still here

Rust

[Taco Cowboy]

At places where iron rusts (oxidizes) you will find the so-called "iron loving" bacteria

But be careful, some of them can cause Tetanus

http://en.wikipedia.org/wiki/Tetanus